I am really surprised that the teachers and staff did not take care of the problem when it occurred if it were such a problem. Every school event or concert I have been to has been well controlled. Regardless of whether or not there was an adult in charge those the kids or not, someone on the school staff would have intervened if it were needed. So, I am wondering if there really was the huge issue that this lady complained about, or if she was being overly sensitive? In any case, she should not have dealt directly with a student, but should have made her complaint through those in charge of the event.